(1) Field of the Invention
The present invention relates to compositions and methods to impart grease resistance and/or water resistance to materials, and more particularly to compositions and methods of improving grease resistance and/or water resistance that are free of fluorochemical compounds.
(2) Description of the Related Art
Materials, such as paper and textiles, are commonly treated or coated to improve their resistance to liquids such as water, grease and oil. Commercial compounds such as Scotchgard™® and Scotchban®, both products of Minnesota Mining and Manufacturing Co. have been widely used to improve the barrier properties of papers, textile fabrics, nonwoven fabrics, upholstery, carpet fibers, and the like.
Scotchgard™® and Scotchban®, and similar products, contain fluorochemicals, which have recently become the object of health and environmental concerns because of their persistence and tendency to bioaccumulate. Consequently, there is strong interest in replacing fluorochemical compounds such as perfluorooctane sulfonate (PFOS), perfluorooctanoate (PFOA), polytetrafluoroethylene (PTFE), perfluoro-n-decanoic acid (PFDA) and other perfluorinated compounds that are widely used for imparting grease, oil, and/or water resistance to the substrates to which they are applied.
Recently several products have been introduced into the marketplace as potential replacements for the fluorochemical compounds. These materials are based on inorganic materials like silica and on organic polymers, or combinations of those materials. However, to date, these replacements have fallen short of the cost/performance standards established by the fluorinated compounds in this area of use.
It is well known to modify the barrier properties of various materials by the addition of a wax, and paraffin waxes have been used in many of these techniques. Examples of the use of waxes for surface treatment, coating, and the like can be found in U.S. Pat. No. 4,117,199. In U.S. Pat. No. 4,097,297 to Keene, an oil and water repellant barrier coating is described that consists essentially of a film forming polymer, a fluorochemical surface tension modifier, and a plasticizer. Waxes, coalescing solvents, and dyes are optionally included.
Poly(vinyl alcohol) has been widely used in films and coatings for properties that range from water dispersibility to barrier properties. Examples of these uses are found in U.S. Pat. Nos. 5,468,526, 5,110,390, 5,283,090, 6,113,978, US 2005/0042443 A1, and GB 2 185 404A, among others. In U.S. Pat. No. 5,981,011 to Overcash et al. a coated sheet material is described that has as one component a barrier coating comprising a polymer mixture in which one polymer can be poly(vinyl alcohol).
Several references describe circumstances where either paraffin wax or poly(vinyl alcohol) can be used for one purpose or another. For example, in U.S. Pat. No. 5,620,793 to Suzuki et al., a printing paper is provided that has no special coating on the printing face and does not cause bronzing in ink-jet printing. The paper also comprises an ink penetration-retarding agent on the printing face that can be, among other things, either poly(vinyl alcohol) or paraffin wax. In U.S. Pat. No. 5,648,164 to Sakaki et al., a recording paper is described in which both poly(vinyl alcohol) or paraffin wax are mentioned as potential ink penetration-retarding agents. In U.S. Pat. No. 6,919,111, to Swoboda et al., a cellulosic multi-ply paperboard is described that contains predominantly cellulosic fibers, a bulk and porosity enhancing additive, and a size press applied binder coating. The paperboard can be coated with either a binder, such as poly(vinyl alcohol), or with a wax. A similar composition having a coating of either a binder such as poly(vinyl alcohol) or a wax is described in U.S. Pat. No. 6,379,497, to Sandstrom et al.
In U.S. Pat. No. 5,843,544 to Andersen et al., hinged starch-bound cellular matrix clam-shell type containers are described that can be coated on the interior with a wax coating. The container can also be coated on the exterior with an elastomeric coating that can comprise poly(vinyl alcohol) in order to strengthen the outer surface and reduce its tendency to fracture during the hinging action. Similar articles produced from a starch-bound cellular matrix reinforced with dispersed fibers and having optional coatings of materials such as poly(vinyl alcohol) or wax are discussed in U.S. Pat. Nos. 5,660,900 and 5,683,772 to Andersen et al.
Wenzel et al., in U.S. Pat. Nos. 5,654,039 and 5,837,383, describe recyclable and compostable coated paper stock comprising a substrate having a primer coat that can be poly(vinyl alcohol) and, in addition, having a top coat that can include a wax composition, which can be a paraffin wax. However, mixtures of primer coat and top coat materials are not described.
In U.S. Pat. No. 5,626,945 to Berzins et al. and U.S. Pat. No. 5,635,279 to Ma et al., repulpable, water repellant paperboard is described that has a coating comprising a wax component that can be a paraffin wax, mixed with a polymer matrix of polymer chains ionically cross-linked through pendant carboxylate groups. A preferred polymer matrix was described as comprising a polystyrene-butadiene polymer copolymerized with a monomer having carboxylic acid pendant groups. In the U.S. Pat. No. 5,635,279; poly(vinyl alcohol) is described as being an ionically cross-linkable polymer that could be used in the invention, however, some carboxylate functionality must be added to the polymer prior to use by copolymerizing with a monomer having carboxylic acid pendant groups.
Other references have described the use of both waxes and substances such as poly(vinyl alcohol) for various purposes, in particular in the field of surface preparations for paper and textiles. For example, U.S. Pat. No. 5,151,404 to Suzuki et al. describes thermosensitive recording paper that does not curl and provides clear images with high image density. The inventors claim that paraffin wax can be used as a sizing agent in the paper, and poly(vinyl alcohol) can be used as a stiffness-imparting agent.
U.S. Pat. No. 5,763,100 to Quick et al., describes recyclable acrylic coated papers that have water and grease resistance and limited moisture vapor transmission characteristics. The papers can have a primer coat, which is commonly a water-based dispersion of a polymer such as poly(vinyl alcohol), and a further coating of a water-based emulsion of an acrylic-styrene copolymer and a wax, which can be a paraffin wax.
In U.S. Pat. No. 5,180,614 to Escabasse, a supple biodegradable sheet is described that is resistant to bursting and has poor water and other liquid absorbing power. The sheet comprises fibers, an optional moisture resisting agent, a binder, which can be poly(vinyl alcohol), a moisture retaining agent, and a sizing agent, which can be a paraffin wax.
Dettling, in U.S. Pat. No. 5,773,131, describes a paper product having a flavor seal and a vapor barrier that is produced by applying a primer coating to the paper that can include poly(vinyl alcohol), and after polymerizing the coating to form an amorphous net structure, applying a cover coating mixture suitable for generating a vapor seal. The cover coating mixture can include paraffin wax.
Dragner et al., in U.S. Pat. No. 5,795,932, describe a surface sizing composition for nonwoven substrates that includes a waxy material, that can be a paraffin wax, but is preferably a stearylated melamine, and a surfactantless vinyl polymer or copolymer emulsion that contains an alkali soluble, acid containing copolymer, which acts as the only surfactant for the waxy material.
In U.S. Pat. No. 5,928,741 to Andersen et al., laminated articles fashioned from sheets having a highly inorganically filled organic polymer matrix are described. The sheets can be coated with various materials, selected to improve water penetration, or grease and oil penetration, or to render the article substantially liquid-tight, or pressure-tight, or to increase the flexibility of the article, and poly(vinyl alcohol) and waxes are included in a list of several possible coating materials. It is stated that mixtures of the coating materials can also be used, but no particular mixture is identified as being preferred. Methods for the production of articles of a similar nature are described by Andersen et al. in U.S. Pat. Nos. 5,580,409 and 5,800,647.
In U.S. Pat. No. 6,159,612, Chu et al. describe multilayer films having a barrier layer containing a wax. The films are said to provide an effective moisture and oxygen barrier without requiring such barrier agents as polyterpenes, alicyclic hydrocarbons, or high barrier polyvinylidene chloride coatings. The films include a layer comprising an olefin polymer, and a barrier layer comprising a syndiotactic polypropylene homopolymer and a wax. They can further include an outer layer that can be coated, for example, with a poly(vinyl alcohol) coating.
Chang et al. describe a method of making a flushable film having barrier properties in U.S. Pat. No. 6,479,105. The film can have a water-dispersible substrate layer that can comprise poly(vinyl alcohol) that is covered with a coating of a low molecular weight amorphous poly(alpha-olefin) that can be admixed with a branched paraffin wax.
In WO 02/14426 to Dixit et al. (also US 2004/0005341 A1) a formulation for providing oil and grease resistance and release paper properties is described as including a fatty acid melamine and paraffin wax emulsion and a poly(vinyl alcohol). Alternatively, the formulation can include a fatty acid melamine wax and a poly(vinyl alcohol). A preferred fatty acid melamine wax is a stearylated melamine wax. The formulation can be used as a coating to provide oil and grease resistance on paper and paperboard, and can also be applied inline on a paper machine.
Despite the advances that recently have been made in the attempt to find effective and environmentally benign alternatives to fluorochemical barrier coatings, there remains a need for compounds or methods that can be used to replace the perfluorinated compounds in present commercial use as greaseproofing and waterproofing agents for paper and the like. It would be useful if such compounds and methods were cost effective and easy to apply. It would also be useful if such compounds and methods were more environmentally benign that the current fluorochemical compounds and it would be useful if such compounds and methods were totally free of such fluorochemical compounds.